Removed actionbar back button.

It was complicating the code base too much.

src/main/java/de/dennisguse/opentracks/AbstractActivity.java

@@ -16,11 +16,9 @@
 
 package de.dennisguse.opentracks;
 
-import android.app.ActionBar;
 import android.os.Bundle;
 import android.speech.tts.TextToSpeech;
 import android.view.Menu;
-import android.view.MenuItem;
 
 import androidx.fragment.app.FragmentActivity;
 
@@ -39,15 +37,6 @@ public abstract class AbstractActivity extends FragmentActivity {
         setVolumeControlStream(TextToSpeech.Engine.DEFAULT_STREAM);
 
         setContentView(getLayoutResId());
-
-        // Configure action bar must be after setContentView
-        if (configureActionBarHomeAsUp()) {
-            ActionBar actionBar = this.getActionBar();
-            if (actionBar != null) {
-                actionBar.setHomeButtonEnabled(true);
-                actionBar.setDisplayHomeAsUpEnabled(true);
-            }
-        }
     }
 
     /**
@@ -55,33 +44,9 @@ public abstract class AbstractActivity extends FragmentActivity {
      */
     protected abstract int getLayoutResId();
 
-    /**
-     * Returns true to configure the action bar home button as the up button (go to previous activity).
-     */
-    protected boolean configureActionBarHomeAsUp() {
-        return true;
-    }
-
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         TrackIconUtils.setMenuIconColor(menu);
         return super.onCreateOptionsMenu(menu);
     }
-
-    @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
-        // Handles actionBar's home menu item (arrow top left corner) and triggers, up navigation to previous activity.
-        if (item.getItemId() == android.R.id.home) {
-            onHomeSelected();
-            return true;
-        }
-        return super.onOptionsItemSelected(item);
-    }
-
-    /**
-     * Callback when the home menu item is selected. E.g., setup the back stack when home is selected.
-     */
-    protected void onHomeSelected() {
-        finish();
-    }
 }